Onychoschizia: scanning electron microscopy

Area of Science:

• Dermatology
• Nail Biology
• Materials Science

Background:

• Onychoschizia is a common nail condition characterized by horizontal splitting.
• The precise cellular mechanism of onychoschizia has not been fully elucidated.

Purpose of the Study:

• To investigate the microscopic structure of nails affected by onychoschizia.
• To determine the cellular layer at which lamellar separation occurs in onychoschizia.

Main Methods:

• Scanning electron microscopy (SEM) was used to examine the distal fingernails of four women diagnosed with onychoschizia.
• Detailed ultrastructural analysis of the nail plate's dorsal surface and tip was performed.

Main Results:

• SEM revealed horizontal lamellar separations, corresponding to single cell layers, on the dorsal surface and tip of affected nails.
• Cleavage lines extended proximally, exposing intricately sculptured cell surfaces within the nail plate.
• These findings indicate that splitting occurs at the interface between adjacent cell layers.

Conclusions:

• Lamellar splitting in onychoschizia occurs between nail plate cell layers.
• This splitting is presumed to result from repeated trauma to nails with compromised cell layer adhesion.
• Dissolution of intercellular cement by common agents like detergents and nail polish solvents likely contributes to diminished cell adherence.